Existing apparatus and machines for dispensing such fluid food products in the mass production industry are generally coupled to a product supply assembly which pressurizes the fluid product at an inlet of the metering device. This enables the device to dispense an appropriate amount of food product at its outlet and onto a conveyor belt or in a tray or pouch for filling it with product. The product supply assembly can for instance include a product container such as a hopper or a canister and a pump, which continuously or alternately extracts the food product from the product container and supplies it to the metering and dispensing device under a pressure level that depends on product viscosity, the amount to be dispensed, and the expected production rate of the line.
Many food products require an accurately measured amount of a filling to be inserted into pouches and trays or as ingredients in the preparation of meals and cakes of every sorts. Previously this has been done by hand which is extremely expensive and time consuming. However, it is necessary that the amount of dispensed food product remains constant and accurate. Indeed, when the receiving medium is over-filled or covered, the manufacturer would have product loss and increased production and raw material costs. To the contrary, when the receiving medium is not provided with sufficient product, the recipe would not meet the customers' expectations.
Several devices and apparatuses have already been developed for accurately metering and dispensing fluid food products. U.S. Pat. No. 5,850,946 relates to a metering device featuring a rotatable metering element in the form of a ball with at least one transverse bore containing a shuttling ball acting as a piston, which can be used for metering gases, liquids and solid particles. The metering element is coupled to a drive shaft and held captive in a casing having opposite passages for inlet and outlet flow of the metered product. In operation, a fluid to be metered is supplied via inlet port and acts on the shuttling ball in the rotating element so that it traverses the rotating element from an extremity to the other, thus dosing a volumetric shot of fluid and expelling an equal volume of fluid via outlet port to a dispensing device. Then, a rotation of 180° of the rotating element is achieved thanks to the drive shaft, and the shuttling ball is again pushed down the bore, dosing a second volumetric shot and expelling the first shot dosed. This is repeated as necessary for dispensing additional dosages or amounts of product.
Such a metering device has an advantage in that it allows for very quick and accurate metering of fluids. However it also constitutes a complicated assembly of many distinct elements which makes it difficult to maintain in case of problems. Furthermore, only very small amounts of fluid product can be dosed and expelled in each working cycle of the device. This does not make such a metering device suitable for food fluid product metering and dispensing in a high quantity food production line. Due to its small capacity, such a metering device is further not suitable for metering semi-fluidic products having food particles therein, such as fruits or meat particles in pies, cream or yogurt, as the device would rapidly be clogged with food in operation. Finally, it is not possible to dose and dispense more than one type of fluid product with the same metering device to increase the production rate of the line.
A possibility to dispense several portions of product with a single machine is disclosed in U.S. Pat. No. 2,551,419, which describes a filling machine for bakery products. A piston provides a pressure on the filling material that is dispersed through a manifold, while a series of valve-controlled ports then releases the product onto a conveyer belt. One shortcoming of this device is that is does not provide for accurate metering of the food product. Another filling device with more than one outlet port is shown in U.S. Pat. No. 4,830,068. This filling machine is capable of simultaneously filling recipients on two separate production lines running in parallel. Dosing and dispensing of the product is achieved by means of a dosing piston and a rotating valve, which aims at regulating the flow of product pressurized by the piston to parallel outlets for dispensing. A major drawback of the device disclosed in U.S. Pat. No. 4,830,068 is that a precise and controlled metering of the product to be dispensed cannot be achieved, and the relatively large size of the machine makes it difficult to implement in a mass production line.
Metering systems based on a slide piston are already known in the art, as for example from U.S. Pat. No. 5,456,298. This patent document discloses a metering apparatus comprising a metering head having diametrically opposite input and output passageways separated by a cylindrical chamber. In the cylindrical chamber is a rotating disk having a passageway that passes diametrically through it and a piston sliding within the disk passageway so that it is simultaneously disbursing and filled with product when it is in alignment with the input and output passageways and then rotated 180°. However, these known systems are rather slow, they do not offer dosing versatility and they cause cavitation problems due to the backstroke of the filler.
Considering the above-mentioned shortcomings of the existing metering and dispensing systems, improvements in such devices are needed.